HTTP/1.1 -1 Read error in cache disk data: SuccessContent-Type: text/tab-separated-values; charset="utf-8" Last-Modified: Sat, 22 Jan 2022 03:08:56 GMT Content-length: 1099 Connection: Close Proxy-Connection: Close X-Cache: HIT from web1.osuosl.org Server: ProxyTrack 0.5 (HTTrack 3.49.2) id summary reporter owner description type status priority milestone component version severity resolution keywords cc lang patch platform 1088 Multidispatch 'concatenate_str' does not handle LHS undef Austin_Hastings "This NQP code prints one line, then fails. {{{ my $x; my $z := '>' ~ $x; say($z); my $y := $x ~ '<'; say($y); }}} The error: {{{ Multiple Dispatch: No suitable candidate found for 'concatenate_str', with signature 'PSP->P' current instr.: '_block11' pc 50 (EVAL_3:27) called from Sub 'parrot;PCT;HLLCompiler;eval' pc 982 (src/PCT/HLLCompiler.pir:548) }}} The generated PIR is `concat $P0, $P1, $P2` for the constant-on-the-left case. But NQP generates `concat $P0, $P1, '<'` for the constant-on-the-right case. It is this case, with an undef first argument, that fails. Changing the constant to a register does not affect the behavior. Storing an empty string in place of the left-hand undef does resolve the problem. I believe the multidispatch doesn't know what to do with undef." bug new normal core 1.6.0 medium undef,multidispatch,concatenate_str he system exit(),ne